The Cardiff University researchers looked at how some people might have the impression of seeing or hear, or feel, the things when there was no stimulus capable of generating this perception. For this they have examined the predictive nature of the brain. They have come to the conclusion that the first symptoms of psychosis would be possible that the alteration of the balance of certain brain functions. But also that what is commonly called hallucinations, was not strictly speaking a sign of a malfunction in the brain, but rather a way of dealing with ambiguous data that he perceived.

Some brains tend to use first the anticipation and knowledge acquired, either transpose what we know, to interpret the world around him. What one sees or perceives is indeed a structure of the brain. “A predictive brain will fill in the blanks so, ignoring what does not correspond to present an image that corresponds to what we expected,” says one of the researchers at the BBC. Even seeing things that do not exist. For example a person with a “predictive brain” perceive a shadow that hid a black cat that takes to their heels, while most will only see a shadow. It is this greater or lesser ability to “fill in the blanks,” or in other words to create images when comes face to something that we do not recognize that explains why some people hallucinate and others no.